I started treatment when I was smoldering because I was high risk. I saw a specialist at Dana Farber that said even though I had a low percentage of plasma cells in my marrow, 99% of them were aberrant. That combined with the fact that I was getting serious infections that required hospitalization, and immunoparesis of both IGM and IGA, I started treatment. RVD induction didn't work, which was a surprise for my team. It is a heterogeneous disease, so your MM specialist will help you decide when to begin treatment.
Treatments have side effects (some are unpleasant and some are permanent). SMM can smolder for a long time. None of the current treatments are cures, so they are held in reserve as long as possible. Think of having a bad sore throat; when do you start treating for strep or pneumonia.
My doctor told me she wanted to preserve organ function.
Seeing a myeloma specialist at a facility that does clinical trials would be ideal. I hope you smolder for a long time. I am reading that a plant based diet might delay progression.